Do not use `patch --merge` in postinstall script
Do not use `patch --merge` in postinstall script

Apparently patch on macOS doesn't have this switch...
see #3592

DirkHoffmann/indico,mic4ael/indico,pferreir/indico,mvidalgarcia/indico,indico/indico,ThiefMaster/indico,mic4ael/indico,DirkHoffmann/indico,mic4ael/indico,indico/indico,pferreir/indico,OmeGak/indico,pferreir/indico,OmeGak/indico,OmeGak/indico,DirkHoffmann/indico,mvidalgarcia/indico,ThiefMaster/indico,indico/indico,DirkHoffmann/indico,mic4ael/indico,mvidalgarcia/indico,ThiefMaster/indico,ThiefMaster/indico,OmeGak/indico,mvidalgarcia/indico,indico/indico,pferreir/indico